return 0 unless $knife == $wknife;
my $part = $part_order[ floor(($colournum-1) / $nknives) ];
die "huh colour $colournum?" unless defined $part;
return 0 unless $knife == $wknife;
my $part = $part_order[ floor(($colournum-1) / $nknives) ];
die "huh colour $colournum?" unless defined $part;